This invention relates generally to an inflation assembly for providing or supplying inflation gas to an associated inflatable passive restraint system for use in vehicles for restraining the movement of an occupant in the event of a vehicular collision. More particularly, this invention relates to providing or supplying such inflation gas via an inflator device having an initiator assembly at least partially mounted within a pressure vessel to rupture a closure element, which normally covers a gas exit opening of the pressure vessel.
It is well known to protect a vehicle occupant by means of safety restraint systems, i.e., “passive restraint systems”, which self-actuate from an undeployed to a deployed state without the need for intervention by the operator. Such systems commonly contain or include an inflatable vehicle occupant restraint element, such as in the form of a cushion or bag, commonly referred to as an “airbag cushion.” In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such airbag cushions may desirably deploy into one or more locations within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, instrument panel or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior.
In addition to an airbag cushion, inflatable passive restraint systems also typically include a gas generator, also commonly referred to as an “inflator.” Upon actuation, such an inflator device desirably serves to provide an inflation fluid, typically in the form of a gas, used to inflate an associated airbag cushion. Many types or forms of inflator devices have been disclosed in the art for use in inflating an inflatable passive restraint system airbag cushion.
Many conventional inflator devices include an initiator and discharge outlet(s) disposed at opposite ends thereof. One such conventional inflator device 20 is shown in FIG. 1. The inflator device 20 includes a gas storage chamber 22 having a base end portion 24 and an opposing diffuser end portion 26. An initiator 30 is positioned at the base end portion 24 and a first burst disk 32 normally covers a base end opening 34 of the gas storage chamber 22 to prevent fluidic communication between the initiator 30 and the gas storage chamber 22. A diffuser 40 is positioned at the opposing diffuser end portion 26 and a second burst disk 42 normally covers a diffuser end portion 44 of the gas storage chamber 22 to prevent fluidic communication between the gas storage chamber 22 and the diffuser 40. Upon activation of the initiator 30, the initiator 30 produces a discharge that ruptures the first burst disk 32 and heats a supply of pressurized gas stored within the gas storage chamber 22. As the supply of pressurized gas is heated, an internal pressure within the gas storage chamber 22 is increased to an internal pressure level sufficient to rupture the second burst disk 42 to provide fluidic communication between the gas storage chamber 22 and the diffuser 40. The heated gas then exits the gas storage chamber 22 through the diffuser 40 to initiate deployment of an associated inflatable airbag cushion (not shown in FIG. 1).
In such conventional inflator devices, the internal pressure within the gas storage chamber typically increases significantly during the initiation stage, thus requiring an inflator device having a sidewall of significant thickness to withstand the increase in internal pressure. The increased thickness of the sidewall may result in an inflator device that is heavier and larger than desired. Additionally, because the initiator is positioned at an opposite end of the chamber with respect to the diffuser, the need to ensure reliable operation, e.g., reliable rupturing of the burst disk, e.g., reliable rupturing of burst disk 42, can serve to effectively limit or restrict the length of the gas storage chamber and hence the quantity of gas stored in the gas storage chamber. Further, the pressurized gas within the chamber is heated to a relatively high gas temperature within the time required to provide an internal pressure sufficient to rupture the second burst disk.
In view of the above, there is a need and a demand for a more reliable inflation assembly for deployment or inflation of an associated inflatable restraint device.
There is also a need and a demand for an inflator device wherein a change in gas storage chamber internal pressure is minimized to allow for the use of a thinner wall material to reduce cost, inflator weight and/or inflator size.
Further, there is a need and a demand for an inflator device including components having a simplified geometry and greater flexibility for different passive restraint systems.
Still further, there is a need and a demand for an inflator device wherein a stored pressurized gas with or without a gas-generating pyrotechnic material can be utilized to inflate an associated inflatable restraint device, depending upon the performance requirements.